There is great interest in the development of polymers with a high barrier to oxygen, carbon dioxide, water, or organic vapors for use in the packaging industry. Various approaches have been taken to improve the barrier properties of polymeric substrates. One most commonly used involves coating an inorganic layer on the top of polymer substrate. The formation of defects in the coating, however, like pin holes or crazes, lead to the formation of a diffusion pathway, thus ruining the barrier properties over time. The incorporation of solid inorganic fillers to improve gas barrier properties of polymers has also been widely used. Incorporating such fillers in large amounts, however, complicates processing due to the inherent increase in melt viscosity. The incorporation also often leads to a loss of optical transparency.